The invention relates to garage door openers. In particular, the invention relates to a releasable trolley for uncoupling and coupling a drive chain to a garage door.
It is well known that garage door opener systems provide safety and convenience for the driver and can be easily operated using a remote transmitting unit. Such a remote transmitting unit, which is typically carried in a vehicle, is used to signal the controller of the garage door opener system, to raise or lower the door, as the driver wishes. Garage door opener systems sometimes become inoperative either due to electrical power outage or, much more infrequently, due to mechanical malfunction. When a garage door opener system becomes electrically inoperative, the drive mechanism remains mechanically connected to the garage door, preventing it from being opened. A number of releasable connectors have been proposed for incorporation into the trolleys, which are reciprocated by the drive chain and connected to hardware attached to the garage door, for selectively disconnecting or mechanically uncoupling the garage door from the drive mechanism.
In U.S. Pat. No. 3,051,014 to Houk for Screw and Nut Mechanism, a garage door opener is disclosed having a carrier 28 which may be selectively connected and disconnected with a drive screw or a worm 26. A skew rack 51 selectively engages or is disengaged from the worm 26. Engagement is controlled by the position of a handle 58.
U.S. Pat. No. 3,443,339 to Goldstein for Release Mechanism For Garage Door Connecting Arm, assigned to the present assignee, discloses a garage door opener having an operating member 26, which may be pivoted by applying tension to a pull cord 27, causing confronting arm portions 28 to be separated from a coupling member pin 32 thereby disengaging the drive of the garage door opener from the door.
U.S. Pat. No. 3,722,141 to Miller for Overhead Door Operator Release teaches a garage door operator having a traveler 40 carried on a track 20. The traveler 40 is connected to be driven by a closed loop consisting of a driving chain 46 and a cable 48 interconnected by a turnbuckle 50. The traveler 40 also is connected to a sectional garage door to be controlled. The chain 46 and cable 48 are connected to the drive unit 22 to be driven thereby. The turnbuckle 50 is releasably retained in a traveler body 60 by a rectangular sliding plate latch 84. The latch 84 is connected to a trip cord 104 which normally holds the latch in connection with the turnbuckle 50 by means of a spring 90, however, the traveler 40 can be disconnected from the drive unit 22 by pulling downward on the trip cord 104.
U.S. Pat. No. 3,591,981 to Law for Door Operator discloses a garage door operator for a canopy type door. The garage door operator includes a manual release for permitting manual operation of the door by allowing a rack 52 to be disengaged from a driving pinion 51, as may best be seen in FIG. 6. This is achieved by pulling on a cord 81 and causing a lever arm 72 to rotate and pull the rack 52 out of engagement with the pinion 51.
U.S. Pat. No. 4,274,227 to Toenjes for Obstruction Sensor For Electro-mechanically Operated Garage Doors, which is assigned to the present assignee, discloses a garage door opener including a two-piece trolley having an outer trolley member 14 and an inner trolley member 16.
U.S. Pat. No. 4,597,428 to Iha for Two Drum Cable Drive Garage Door Opener, assigned to the present assignee, discloses a garage door opener having a trolley 51. A pawl 57 is slidably received in an opening in the trolley 51 which engages a notch 56 in the member 54 when the trolley 51 is locked to a cable 38. A spring 61 biases the pawl 57 into the notch 56. In order to release the door from the drive unit, a rope 62 connected to the pawl 57 is pulled downward by a handle 68 to draw the pawl out of engagement with the member 38.
It is also well known in the prior art to provide lock out mechanisms wherein a pawl of the type disclosed by Iha may be rotated slightly at the bottom of its travel and locked out of engagement with the cable or the drive unit. Unfortunately, until recently, separable trolleys of the type having an inner trolley which travels with the drive chain, an outer trolley which travels with the garage door, and a latch arm carried by the outer trolley which pivots about a pivot pin, have not had a lock-out feature. This lack of a lock-out feature prevented users of two-piece trolley garage door openers from locking the inner and outer trolleys in a disengaged state until such time as they are to be reengaged.
What is needed then is a two-piece trolley system with a latching arm and a lock-out feature.